The state of the art in setting type provides phototypsetters capable of producing high resolution characters at high speed, for example at speeds up to 4,000 characters per second, and the setting of newsprint at 1250 lines per minute. The media upon which this typesetting is produced is photographic film or paper intermittently fed from a roll supply varying in width from three to seventeen inches. The media has a photo sensitive emulsion that is exposed through a make-up area or aperture to a cathode ray tube and a lens system or the like, whereby photocomposition is attained. A feature of newsprint and the like is that the typesetting is organized into columns or galleys. For example, a newspaper will be comprised of six columns and separated into different news articles between the top and bottom of the page. Accordingly, page composition requires the starting and stopping of the typesetter, for the separation and arrangement of news article in sequence and in side by side relation, including spaces for pictures and the like. Separation is referred to as "leading" when progressing forward or downwardly, and as "reverse leading" when reversing the film media and setting other columns of type adjacent to previously set columns of type. Therefore, it is an object of this invention to provide a storage means for film media ahead of and behind the make-up area or aperture, so as to enable both "leading" and "reverse leading" within the phototypsetter per se.
This invention relates to the handling of exposed media in phototypesetters, wherein film is transported through an aperture from a supply to a take-up. Fragile media such as photographic film is to be transported for exposure without scratching or marring, and moved under low constant tension with minimal inertia, so that it can be accelerated and decelerated quickly. The media is caused to move forward and backward, and friction is to be minimized; and in these respects it is an object herein to advantageously employ a lens system to project images written on a cathode ray tube and onto film media in motion. This is in preference to the use of fiber optic face plate tubes over which the film must be dragged. Accordingly, with the present invention the film media or paper is tensioned between the supply and take-up by unique means that minimizes inertial mass so that there is extraordinarily little friction or drag.
A feature of this phototypsetter transport is its encoder means that is used to measure movement of the media and synchronize the typesetting function by displacing the image written through the optics and onto the moving media in response to said movement thereof. It is an object therefore to provide a transport system with buffer means in the form of a supply pocket and a take-up pocket adapted to maintain a substantially constant tension upon the media as it spans the make-up area or aperture. With the present invention, vacuum pockets are provided to receive loops of media, and as shown to enable reverse leading for example up to 26 inches. In practice, separate systems are used to feed media into the supply pocket and into the take-up pocket, and sensor means at said pockets monitors the media therein; so that when the supply pocket becomes too empty, a feed means brings in more media from the supply; and so that when the take-up pocket becomes too full, a take-up means pulls the media therefrom for delivery into the take-up. A characteristic feature of this transport system is that in moving the media through the make-up area or aperture, the said media is not pulled from heavy rollers or shoved into a crowded take-up area. On the contrary, the involved mass is reduced to that of the media alone, and the tension to be counteracted is produced by the vacuum only as it is regulated at the two pockets.
The state of the art provides media in supply and take-up cassettes, and it is common practice to transport film media with pinch rollers. Accordingly, the present invention employs pinch roller drive means from a supply cassette. However, with the present invention it is an object to tension the media by means of a vacuum pocket, and to this end the media is drawn tight across the make-up area or aperture as said media extends from a supply pocket to the pinch rollers of the drive means. And, additionally there are pinch rollers of a supply means responsive to the aforesaid pocket sensor means to feed the media into said pocket on demand. Similarly, it is an object of this invention to remove exposed media by means of pinch rollers of a take-up means, and to this end the media is drawn from a take-up pocket where it is held taught by a vacuum when delivered thereto by said drive rollers. This is significant in that the media is held in taught equilibrium across the make-up area.
A deficiency in prior art phototypesetters has been the alignment of media as it feeds from the supply cassette. Reference is made to supply cassettes that are supposedly installed in alignment and which journal the spool or core of film media substantially but not exactly aligned, thereby requiring realignment means to receive the film media supplied by the said cassette. With the present invention alignment is inherent, it being an object of this invention to align the cassette core with the transport mechanism and to permit the case of the cassette to float. In this respect the core of the cassette is accurately produced with facility and turns upon centers that are adjustable as to media width, all as circumstances require.
A deficiency in prior art phototypesetters has been the difficulty of threading of and the limited capacity of the take-up cassette. It is therefore an object of this invention to provide self threading and to substantially increase capacity by a direct cooperative relationship with the take-up means as it operates independent of the drive means to fill the cassette. And, intermediate the closely associated take-up means and take-up cassette there it is cutter means that trims and separates sections of media which is self threading into said cassette through a light trap. In practice, the take-up means and take-up cassette have a common drive means.